The primary automatic transmission to use a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was introduced for the 1948 model calendar year. In ordinary driving, the Dynaflow made use of just the top rated equipment, counting on the torque multiplication from the torque convertor at https://gearbox-auto21852.blazingblog.com/34161912/gearbox-auto-fundamentals-explained